Automatic ice cube maker



Jan- 28, 1969 M. G. LEEsoN ETAL.

AUTOMATIC ICE CUBE MAKER Filed April 28, 1967 Sheet GERALD LL'L-so/vHAROLD H. 5555/? 5 f7, 7%@

344 ,80 MEL 00N `iam. 28, 1969 M. G. LEEsoN ETAL 3,423,949

AUTOMATIC ICE CUBE MAKER Filed April 28. 1967' )NVE/vrom. Mano/v GERM@E550/v Hmow H. 5555/? www United States Patent O 3,423,949 AUTOMATIC ICECUBE MAKER Meldon Gerald Leeson, Berwyn, and Harold H. Esser,

Chicago, lll., assignors to Schneider Metal Manufacturing Co., Chicago,Ill., a corporation of Illinois Filed Apr. 2S, 1967, Ser. No. 634,606U.S. Cl. 62-73 29 Claims Int. Cl. F25c 1/12, l/ZZ, 5/08 ABSTRACT OF THEDISCLOSURE An automatic ice cube maker having a grid for dissecting aslab of ice to form ice cubes, the grid consisting of a substantiallymonoplanar lattice of heated wires dening closed meshes so that the slabis cut through simultaneously along intersecting planes; a controlsystem for timing and recycling ice production, the control systemhaving an ice harvesting timing mechanism and a temperature sensor tooverride the timing mechanism when the full allotted time is notrequired for ice harvesting operations; and sensor means to term'matefurther production of ice cubes when ice cuzbes accumulated in a storagebin exceed a predetermined level.

This invention relates to ice maker apparatus of the type whichautomatically produces ice cubes or cubelets. More particularly, theinvention is directed to an improved cutting grid and to an improvedcycling and control system for automatic ice cube makers.

Many ymachines for producing ice cubes automatically are known in theprior art, and these machines have taken various physical forms and haveutilized various engineering mechanisms and techniques. Both mechanicaland thermal means have been used to produce cubes of ice from largerlblocks or slabs. In ice cutting apparatus utilizing thermal means,electrically heated wires have been widely employed as the cuttingelements, and these electrically heated Wires, or their functionalequivalents, have been arranged in parallel arrays to dene blockorslab-cutting elements. In forming ice cubes from block ice, the cuttingoperations must be carried out in three planes at right angles to eachother, and this operation has been achieved through the use of threeseparate sets of parallel wires, the wires of each set being positionedso as to cut the ice in the three planes at right angles to each other.In forming ice cubes from slabs of ice, the prior art technique has beento use two separate grids which are spaced from each other and whichcarry separate parallel arrays of wires disposed at right angles to oneanother. It is to a novel single grid slab-cutting apparatus, whichconstitutes a marked improvement over the above described two-gridsystems, that one facet of the present invention is directed.

Ice maker apparatus of the type in which a slab of ice is formed on theevaporator plate as a result of owing water over the plate while theplate is suitably refrigerated is well known in the prior art. In suchapparatus the slab forming refrigerated plate is conventionally slightlyinclined facilitating the desired water flow and permitting the finishedice slab to slide downwardly, along the plate, when ulti-mately freed.In the prior art machines the released slab is guided to fall upon agrid of parallelly disposed cutting means such as electrically heatedwires, and a second, separate grid spaced below the first grid andsupporting an array of parallel wires disposed transversely of the rstset of wires completes the slab cutting means so that the slab may becut into a plurality of discrete units constituting prisms, cubes, orthe like.

While the improved grid or lattice of the present invention `findsutility in the ice slab-forming apparatus of the above described type,the present invention is described herebelow with reference to an icemaker in which the slab of ice to be transformed into cubes is formed onthe underside of a refrigerated plate or an evaporator. Although theconcept of forming an ice slab on the underside rather than on the topsurface of an evaporator plate is not broadly new, the present inventionincludes important engineering advances in this type of ice maker.

It `will readily `be appreciated by those skilled in the art that indelivering a slab of ice from` the unders-ide of a freezing plate ontoan ice cutting grid supported therebelow, the slab may be droppeddirectly downwardly onto the grid, thus obviating any need to shift theslab generally lhorizontally to clear the freezing plate, as required inthe case of slabs formed on top surfaces of evaporator plates. That is,important space saving is achieved through the use of the apparatus ofthe present invention in which the slab is formed on the underside of anevaporator plate. Other advantages associated with this structure willbecome evident as the description proceeds.

One facet of the present invention is directed to a structure andtechnique Vby means of which a slab of ice may be simply andconveniently dissected or otherwise transformed into prisms or cubes ina single thermal cutting operation utilizing only a single grid, thecutting of the slab along transverse planes being effectedsimultaneously.

The release of slabs to fall upon wire grids supported therebelow hassubjected these grids to life-shortening shocks and stresses. It is afeatureof the present invention that the relatively heavy slab isdelivered to interwoven or interlaced, or otherwise crossinginterconnected weight-distributing ice cutting elements which constitutethe improved slab cutting lattice of the invention. In a preferredembodiment of the invention, the ice cutting, lattice-forming elementswhich traverse and bridge the opening dened by their encircling frameare coupled to or otherwise attached to the lattice framing membersthrough shock-absorbing structures such as spring means which maintainthe cutting elements tensioned yet resiliently responsive to forcesimpinging thereon yieldingly to absorb these forces.

The force of the falling slab of ice, is, in accordance with thepractice of the present invention, distributed substantially uniformlyover the entire area of the ice cutting lattice, since one Set ofparallelly .arrayed ice cutting elements is in direct physical contactwith a second generally transversely disposed array of cooperating icecutting elements.

It is a principal feature of the present invention that electricalenergy is supplied to the grid across spaced parallelly extending busbars in a manner to heat Simultaneously all segments of the latticewhich define the closed meshes of the unitary grid structure. In apreferred embodiment of the improved ice cutting grid of the invention,the novel lattice grid comprises parallel electric-al circuits in whichthe conductive paths between opposed terminals are zig-Zag or saw-toothin form.

Another feature of the invention is a control system which automaticallyfrees the formed ice slab from the evaporator plate and deposits it onthe ice cutting grid. An important feature of this control systemcomprises means for sensing that the ice has dropped off the evaporatorplate and for immediately initiating the remaining phases of theharvesting and recycling operation. This novel feature eliminates anynecessity for waiting out 4a fixed duration of the timed operation, andcauses the machine to resume ice production quickly and efficiently. Theadvantages of a timed ice harvesting operation are retained with theimprovement of la sens-or which overrides the timer to cut short theunneeded portion of the ice harvesting time period.

Yet another feature of the invention is a structural arrangement bymeans of which the level of ice cubes contained in a collector orstorage bin disposed below the ice cutting grid may be sensed ordetected when that level has reached a predetermined height, the sensingmeans being operative to effect termination of further freezing and ice'cube making cycles so that ice cube production will not exceed theneed.

Other features and advantages of the invention will become apparent froma reading of the following specication taken in conjunction with thedrawing in which:

FIGURE l is a perspective View of an ice maker which includes a slabdissecting grid assembly embodying the invention;

FIGURE 2 is a top plan view of one embodiment of a grid or latticehaving a structure in accordance with the teachings of the invention;

FIGURE 3 is an enlarged fragmentary view, partly in section, showing theportion of the grid circled in FIG- URE 2 and showing interlinkedclosed-mesh-dening wire elements and resilient grid wire anchoringmeans;

FIGURE 4 is a top plan view of a second preferred embodiment of theice-slab-cutting grid of the invention;

FIGURE 5 is an enlarged fragmentary view, partly in section, showing theportion of the grid circled in FIG- URE 4 and showing an interwoven meshstructure, resilient support means, -and means connecting theice-cutting wire to an electrical bus bar;

FIGURE 6 is a side elevational view of the ice-slabcutting grid assemblyshowing the mechanism for raising and lowering the grid assembly, andshowing the ice cube detecting mechanism for suspending ice cubeproduction when the ycubes have reached a predetermined level.

FIGURE 7 is a schematic diagram showing the electrical control circuitof the invention;

FIGURE 8 is a diagram showing the refrigeration and ice freezing systemof the invention; and

FIGURE 9 is a front elevational view showing the cam for actuatingcontrolling microswitches, which cam is driven by the grid gear motor.

Two preferred forms of the grid of the present invention, provided onlyfor the purpose of illustrative disclosure and not by -way oflimitation, are depicted in FIG- URES 2 and 3 and FIGURES 4 and 5. Inthe drawing, the perspective View, FIGURE l, shows an ice makerincorporating the features of the invention and including the novel gridstructure. The ice maker 10 includes a refrigerated plate or evaporatorplate 12, and a water jet tube 16 for supplying water to the underside18 of the evaporator plate 12 to build `an ice slab 22 thereon. Thefreezing plate 12 is inclined downwardly from front t0- Ward the rear,and owing water 24 in excess of that transformed into ice on theevaporator plate 12 is received in a collecting trough 26 positionedbelow the evaporator plate at its lower end. The water collected in theItrough is subsequently and continuously recirculated to the plate 12through a pipe 32, by means of a suitable pump 36. In a preferred formof the invention the water recirculated is ultimately automaticallydiscarded as waste so that build-up of objectionable solids in the Watersystem is avoided. Control is effected through water dump solenoid 37.

Refrigerant is supplied to the evaporator 12 through a suitable pipe 40from a conventional refrigeration assembly (not shown). A slab of ice isbuilt up upon the underside surface of the evaporator plate 12 yand whenthe ice slab 22 has reached the desired thickness, the plate is heatedso that the slab 22 is freed and drops upon the frame-supportedice-cutting grid assembly 44 which is disposed below the plate 12 insubstantial vertical correspondence therewith. While any preferred slabthickness sensing devices such as optical, mechanical or electricalsensors, or timers may be used, and while any preferred slab-freeingtechnique may be employed, in the preferred embodiment of the presentinvention a timer is used to control the ice thickness, and warm fluidis circulate-d through the evaporator plate to free the ice slab. Theice slab 22 is supported upon the heated ice-cutting means 48 which melttheir Way into the ice slab, the slab advancing downwardly by gravity topass through the grid 44 as the ice `slab 22 is dissected into discreteunits such as prisms, cubes 50, or the like, the formed cubes fallinginto a storage receptacle or bin 54 below the ice cutting grid 44.

The ice slab cutting grid assembly 44 includes a frame 56 which ispreferably generally rectangular in form and comprises a pair ofrearwardly spaced parallel channel bar frame members 60 and 62 connectedto one another at their respective ends by means of a transversely eX-tending pair of laterally spaced parallel frame members 66 and 68. Theframe 56 is pivotally mounted by means of U-shaped slots 70 which Iareformed in plates 74 fastened to the frame 56 at opposed rearward lateralportions thereof, the slots 70 receiving therewithin cooperating pivotpins or hinge rods 78 so that the frame 56 is journalled for arcuatemovement through a vertical plane. A frame-supporting link S0 providedwith a slot 82 is coupled -at its lower end to a rod or pin 84 fastenedto and extending laterally outwardly of the frame 56 at a positionsubstantially midway along the length of the side framing member 68 asshown in FIGURE 6. At its upper end the link is fastened to and dependsfrom a crank arm 88 fastened to the drive shaft 90 of a motor 92 throughwhich assembly the frame 56 is pivoted between a lower, substantiallyhorizontal position, to -a rearwardly tilted sloping position, as morefully described hereinbelow.

It is a most important facet of the inventive concept of this inventionthat electrically heated ice slab cutting elements form a substantiallyplanar integral unit and dene a lattice of cutting segments the ends ofwhich are in contact electricallyto provide an array of closed meshes.Within this novel .and inventive concept, it is contemplated thatvarious structural arrangements may be used to provide lattices or gridsoperative in `accordance with the principles of the invention, oneexemplary physical structure being illustrated in FIGURES 2 and 3, and asecond embodiment being shown in FIGURES 4 and 5.

Referring more particularly to the drawing, and rst to FIGURES 2 and 3,there is shown, for the purpose of illustrative disclosure, onepreferred form of the invention including a novel lattice structure.Opposed forward and rearward framing elements 60 and 62 of the frame 56carry electrical terminal strips or bus bars and 102 which areelectrically insulated from the Vframe 56, the terminal strips beingconnected to the secondary or output of a step-down transformer 110, thelatter being indicated schematically in FIGURE 2 and serving to reduce asupply voltage, such as a conventional volts supply to a low value,which in the particular embodiment of the invention shown isconveniently in the range of about 3 volts. Electrically resistiveice-cutting elements or wires 114 provide conductive paths between theopposed terminal strips 100 and 102, the passage of current through thewires 114 effecting the required heating for cutting the ice slab, Thelateral framing elements 66 and 68 of the grid frame 56 are insulatedelectrically from the terminal strips 100 and 102 and form no part ofthe electrically conductive circuit.

In the structures of FIGURES 2 and 3, the heated wires 114 which formthe lattice execute zig-zag or sawtooth paths between the forward 100and the rearward 102 conductors of the electrical supply system. As seenmost clearly in the enlarged detail of FIGURE 3, a given wire element118 is intercoupled or looped around its next adjacent cooperatingelement 120 in a manner suggestive of widely used linked wire fencing.The extreme lateral elements or runs are supported at linearly spacedpositions along the side framing members 66 and 68, points of supportalong these framing members being electrically insulated from the frameitself, as shown in FIGURE 3. The points of support of the lattice alongthe forward and rearward framing elements 60 and 62 are connectedelectrically to respective bus bars 100 and 102 so that the overalllattice defines a plurality of parallel electrical networks extendingbetween the opposed conductors 100 and 102. Through this novelarrangement all segments of the lattice are electrically heated tosubstantially the same temperature so that even cutting of ormelt-through of the ice slab is achieved.

When freed from the underside 18 of the evaporator plate 12, the iceslab 22 drops downwardly onto the cutting grid 44 (FIGURE l). In apreferred embodiment of the present invention, in order to absorb theshock associated with the ice slabs falling onto the grid, the icecutting means or grid wires 48 are resiliently mounted or tensioned onthe grid frame 56, one preferred embodiment of a grid wired tensioningassembly being illustrated in FIG- URE 3. As shown, the tensioning andshock absorbing assembly 126 includes a rod 128 which extends throughand is resiliently mounted against a side-wall 130 of the framing member66. A anged insulating bushing or grommet 134 extending through anopening 136 in the side wall or web 130 isolates the wire tensioningassembly 126 electrically from the frame 56. At its inward end the rod128 is provided with a slanted slot 140 into which the grid wire isinserted, and a spring 142 interposed between the insulating bushing 134and a nut 144 threaded on the end 146 of the rod 128 resiliently urgesthe rod laterally outwardly from the frame to maintain the grid taut andtensioned. While in the particular wire-tensioning assembly illustratedthe spring comprises a coiled element, other types of springs such asband or leaf springs 150 may be used. Such an arrangement is shown inFIGURE 5.

Referring now to FIGURES 4 and 5, there is shown a second mechanicalembodiment of the improved grid structures of the invention. Whereas inthe structure of FIG- URES 2 and 3 the conductive elements areintercoupled or interlinked at their contact points, the conductiveelements 160 of the grid illustrated in FIGURE 4 and in the enlargeddetail of FIGURE 5 form a woven lattice in which a given linearlyextending wire element 164 follows a path which alternately goes overand then under cooperating wire elements 166 and 168 extending generallytransversely of the given element. Notwithstanding the clearly evidentmechanical differences in the two preferred embodiments of the inventionshown, the equivalent electrical circuits of the two forms of the gridor lattice are the same. In 'both grid structures each incrementallength of any given conductive element is heated to substantially thesame temperature as other incremental potrions of the lattice so thatthe slab is cut through evenly.

The closed mesh lattices of the present invention may be fabricatedusing a single length, a double length, or any preferred number ofseparate wires. In order to provide a practical commercial structure andto simplify servicing and repair procedures, the lattices of theinvention are preferably fabricated using a plurality of wires, and itis an important feature of preferred forms of the invention that isparticular lattice configurations, all wires are of equal length.Referring first to FIGURES 2 and 3, each of the wires 114 defines astepped, saw-tooth, or zig-zag configuration as it extends between thebus bars 100 and 102 and opposed parallel framing elements 60 and 62. Inthis 6 grid form, each wire is intercoupled or linked, alternately, withwires at either side (FIGURE 3). In the lattice of FIGURES 4 and 5, theice cutting wires 160 extend along L-shaped paths the legs 164 and 16411of which are angled with respect to the bus bars and to the opposedframing members to which ends of the wires are anchored, Al-

though for different wires the lengths of respective legs will differ,in each case the combined lengths of the legs is the same for each wire.It will be appreciated that the use of one wire length reduces stockrequirements and greatly facilitates rep-lacement of any broken wires.

Any preferred mechanical means and technique may be used to connect theice cutting means 48 to the currentsupplying bus bars and 102 onesuitable arrangement being shown in FIGURE 5. The bus bar 100 isprovided with linearly spaced lugs, posts, or bosses 172 extendingperpendicular to a plane defined generally by the wire lattice. The endsof the wires are formed with closed loops 176, these looped portionsbeing anchored over the posts 172, and the wire then passing throughopenings 178 in the frame element. Alternatively the anchored wires maybe guided over a longitudinally extending edge of the bus bar.

While the use of wires as ice slab cutting elements constitutes apreferred mechanical means, the grids of the invention may be formed byother methods as well, such as by stamping, expanding techniques,electroplating, and through printed circuit techniques.

During ice cutting, as well as during intervals between ice slab cuttingoperations, or in its rest or standby position, the ice-cutting gridassembly 44 is supported over the ice storage bin 54 in a generallyhorizontal plane. While the heated grid is melting its way through theice slab supported thereon, a second ice slab is being formed on theunderside of the evaporator plate 12. The rate at which heat energy issupplied to the cutting wires of the grid is such that these wires willmelt through an ice slab in somewhat less time than is required for asubsequent slab of the desired thickness to be produced. The cubes fromthe dissected slab pass through the grid and are deposited in the bin56.

When the ice slab thickness control element, which is preferably atimer, but which may be an electrical or mechanical sensor, is actuatedindicating that the new slab has reached a predetermined thickness, Warmgas or lluid is circulated through the channels of the evaporator plateto free the frozen slab. At the same time the motor 92 is energized tolift or pivot the grid 44 toward the evaporator plate so that thedistance through which the freed slab falls is minimized. After the iceslab falls upon the grid, the motor 92 is actuated and the grid moves orpivots downwardly to assume a substantially horizontal position, thisposition being -maintained throughout the cutting operation so thatright prisms are formed from the ice slab.

The preferred embodiment of the invention may be considered, forpurposes of disclosure, as consisting of four cooperating systems: therefrigeration system, the water system, the ice cutting system, and thecontrol system. The ice cutting system has been described above indetail, and the three remaining systems are described below.

The operation of the refrigeration system shown in FIGURE 8 is asfollows: A compressor 202 circulates refrigerant through a condenser204, a receiver tank 206, and a drier-strainer 208 and through anevaporator 212 to form an ice slab on the underside of the evaporatorplate 12 of FIGURE 1. When an ice slab of predetermined thickness hasformed on the evaporator plate 12, and upon command from the controlsystem, the hot gas solenoid 210 opens to permit hot refrigerant gas toflow into the evaporator 212 directly from the compressor 202. The hotgas heats the evaporator plate 12, freeing the ice slab which then dropsonto the frame-supported ice cutting grid assembly 44. When the iceseparates from the evaporator plate 12, a thermostat switch 310 sensesthe hot refrigerant, closes the hot gas solenoid 210 and opens theexpansion valve 209 to initiate a new freezing cycle.

Operation of the water system is described with reference to FIGURE 1.Water is introduced through a conventional float valve (not shown) intoa collecting trough 26. A water pump 36 pumps water from the trough 26through a conduit 32 to the higher end of evaporator plate 12, the waterthen flowing across the underside of the evaporator plate 12 whereby aportion of the water freezes to form a film of ice. The remaining waterreturns to the trough 26 to be recirculated. The process continues untila slab of the desired thickness is formed. At the beginning of the iceharvest cycle, a water dump solenoid 37 opens to effect discharge of thewater in the trough 26 thereby eliminating all accumulated objectionabledispersed solids. The water pump 36 then turns off. At the end of theice harvest cycle the water dump solenoid 37 closes and as the freezingcycle is reinitiated the water pump 36 is restarted.

The control system is illustrated schematically in FIG- URE 7. A sourceof electric current is fed through a main switch 302 to operate selectedcombinations of components to control the freezing and harvestingcycles. Time switches 306i, 306 and 306iz'z', of conventional design,are operated by the timer motor 308; and any selected switch may beactuated to provide a choice of a twenty-two minute, thirty minute, orforty-five minute ice production cycle followed by a 4 minute iceharvest cycle. The freezing operation is initiated by actuating one ofthe time switches 306. At the beginning of the freezing cycle, thefollowing components are energized: the grid power transformer 110, thecompressor motor, the timer motor 308, the condensor fan 95, and thewater pump 36. At the beginning of the ice harvest cycle, the hot gassolenoid 210, the water dump solenoid 37 and the grid gear motor 92, areswitched on, while the condensor fan 95 is switched off. The grid gearmotor 92 raises the grid assembly 44 to receive the ice slab as water isdrained, and heated refrigerant ows into the evaporator 212 to free theice slab from the evaporator plate 12.

After the grid gear motor 92 has lifted the cutting assembly 44 to theup position, the grid gear motor 92 is switched off, as is the waterpump 36. The ice drops yfrom the evaporator plate 12 onto the grid wires114. After the ice is freed from the evaporator plate 12, or after apredetermined time, the grid gear motor 92 is again energized to lowerthe grid assembly 44. The hot gas solenoid and water dump solenoid 210are closed, and the condenser fan 95 is again turned on to begin a newfreezing cycle.

The prescribed sequential actuation of the above described components isaccomplished by means of the novel control system shown schematically inFIGURE 7. A microswitch 312 controls the water pump 36, and `a secondmicroswitch 314, the grid gear motor 92. Microswitches 312 and 314 areactuated by a cam 320 (FIG- URE 9) driven by the grid gear motor 92. Itis an important feature of the invention that the evaporator thermostatswitch 310 operates to override the four minute timer if the ice slab isfreed from the evaporator plate 12 in less than four minutes. Thus, whenthe grid assembly 44 is raised to receive an ice slab, if the slab dropsfrom the evaporator plate in a time less than four minutes, theevaporator thermostat switch 310 is actuated by the hot gas passingthrough the evaporator 12 to terminate the ice harvest cycle and resumethe freezing cycle without waiting for the full four minute time periodto elapse.

The operation of the control circuit is more clearly shown when theschematic circuit diagram of FIGURE 7 is considered in conjunction withChart I which shows the position of the controlling switches at eachphase of the freezing and ice harvesting operations.

CHART I.-SWITCH POSITIONS Switch Numbers Phase I: Freezing in progress;grid assembly in down position A A A B B A Phase II: Start of iceharvest; grid assembly going up A A B A B A Phase III: Ice harvest inprogress; grid assemblyinup position A A B A A B Phase IV:

(a) Ice harvest ended by actuation of evaporator thermostat; gridassembly going down A A B B A B (b) Ice harvest ended by actuation offour minute timer A A A A B A Another important feature of thisinvention is an ice sensing system which operates to suspend iceproduction when the bin contains an adequate supply of ice cubes. Asshown in FIGURE 6, an ice sensing b'ar 340 is fastened to and extendsdownwardly from the grid assembly 44, and an extension link 344,fastened to the grid assembly 44, extends upwardly thereof toward amicroswitch 304-. If the ice cube level exceeds a predetermined maximum,when the grid assembly 44 is lowered, the ice sensing bar 340 will abutthe stored ice cubes and the grid will stop i-ts downward travel. Theslotted frame supporting link 80, and the microswitch 304 continuedownwardly until the extension link 344 contacts and opens themicroswitch 304 to turn off the machine. When the ice cube level drops,the microswitch 304 opens and the machine resumes ice production. Thisnovel automatic cut-off systern precludes the possibility of turning offthe machine while an ice slab remains on the evaporator plate 12 fromwhich it could drop to damage the grid assembly 44. It also assures thatthe machine will restart each time on a full production cycle. Sincethis cut off system does not utilize a thermostat, it is not affected byambient temperiature and would thus permit turning of the grid heatingcurrent during dormant periods.

It is to be understood that the specific embodiments of the inventionshown in the drawings and described above are merely illustrative of themany forms which the invention may take in practice without departingfrom the spirit of the invention or from the scope of the invention asdefined in the appended claims.

What is claimed is:

1. In an ice maker apparatus including means for forming a slab of iceand means for causing said slab to bear upon ice-cutting means fordissecting said slab, said icecutting means including a frame andframe-carried icecutting elements', the improvement wherein, in use,said ice-cutting elements define meshes of a lattice consisting ofcontacting, crossing, electrically connected and resistively heatedice-cutting segments; and electrical circuit means operatively coupledto said ice-cutting elements and developing resistively generatedthermal energy therein for heating of said elements to cut through saidslab of ice bearing thereon.

2. A lattice as set forth in claim 1 wherein said icecutting meanscomprise electrically heated wire means in electrical contact and lyingin substantially the same plane, said ice-cutting means defining a gridfor cutting said slab of ice bearing thereupon.

3. A lattice as set forth in claim 2 wherein said icecutting meanscomprises woven means forming a unitary grid of closed meshes withinsaid frame.

4. The structure as set forth in claim 3 wherein said lattice comprisesa plurality of separate Wires crossing and contacting one another andextending between framing members of said frame to define a grid ofclosed meshes.

5. The structure as set forth in claim 2 and further comprising anchortrneans resiliently mounting said wire means in said frame.

6. The structure as set forth in claim 3 wherein said wire meanscomprises electrically conductive wires interlinked to form a generallyplanar network of closed meshes.

7. The structure as set forth in claim 2 wherein said wire means of saidlattice execute L-shaped paths within said frame, said fname beingsubstantially rectangular in outline, and further comprising meansanchoring opposite ends `of said wire means on corresponding oppositeparallelly disposed frame members, and means supporting said wire means,intermediate ends thereof, on a frame member interconnecting andextending transversely of said parallelly disposed frame members.

8. The structure as set forth in claim 3 wherein said Wire means executezig-zag paths between opposed parallel grid support members of saidframe.

9. The structure as set forth in claim 2 wherein said frame defines agenerally rectangular opening and wherein said wire means extend betweenand interconnect a pair Iof opposed grid-support members of said frame,said structure further comprising electrically conductive meansconnected to said wire means adjacent said opposed grid support membersand adapted to deliverelectrical energy to said wire means to lheat saidgrid resistively.

10. The structure as set forth in claim 1 and further comprising meanssupporting said frame for movement through a vertical plane.

11. The structure as set forth in claim 1 and further comprising anice-storage bin positioned below said frame to receive ice deliveredtherefrom, sensing means carried by said frame for movement therewithand extending downwardly of said frame-carried lattice and toward a topopening of said bin, said sensing means being operative to detect ice insaid bin when ice accumulated therein fills said bin above apredetermined level, and

switch means coupled with and responsive to said sensing means toterminate freezing operations of said ice maker when the level of ice insaid bin is above said predetermined level.

12. The structure as set forth in claim 11 and further comprising meanssupporting said frame for movement through a vertical plane extendingupwardly of said bin, whereby upon movement of said frame downwardlytoward said bin said sensing means enters said bin to detect ice presenttherein above said predetermined level.

13. The structure as set forth in claim wherein said means supportingsaid frame supports said frame for arcuate pivotal movement.

14. 'l'he structure as set forth in claim 12 wherein said meanssupporting said frame supports said frame for arcuate pivotal movement.

15. The structure as set forth in claim 13 and further comprising motormeans for controlling the pivotal movement of said frame.

16. The structure as set forth in claim 14 and further comprising motormeans for controlling the pivotal movement of said frame.

17. The structure as set forth in claim 15 and further comprising switchmeans responsive to separation of an ice slab from said ice formingmeans to actuate said motor means to pivot said frame toward said bin.

18. The structure as set forth in claim 16 and further comprising switchmeans responsive to separation of an ice slab fromsaid ice forming meansto actuate said motor means to pivot said frame toward said bin.

19. The structure as set forth in claim 3 wherein said frame defines agenerally rectangular `opening and wherein said wire means carried bysaid frame extend between a pair of spaced generally parallel opposedframing members and cross said opening to bridge said opening alongpaths which are greater in length than the distance between said opposedframing members.

20. The structure as set forth in claim 19 and further comprisingcircuit means suppling wire-heating current to said wire means along aconductive path generally parallelling `a pair of said opposed framingmembers of said frame.

21. In the method of forming ice cubes wherein a slab of ice is cut byheated slab-supporting ice-cutting means upon which said slab is broughtto bear, and wherein the cutting operation is carried out so as to cutthrough said slab generally transversely of a principal face thereof,the steps comprising liowing water on a refrigerated plate to form aslab of ice thereon,

freeing said slab from said plate,

depositing said slab to bear on a lattice of ice cutting elementsincluding electrically conductive crossing segments electricallyconnected at cross over points.

and lying substantially in the same plane and defining a grid of closedmeshes,

applying electrical power to said lattice to heat said crossing segmentsresistively and to develop thermal energy in each of said ice cuttingelements of said lattice upon which said slab is brought to bear, and

cutting said slab simultaneously along substantially coplanarintersecting lines defined by said grid of closed meshes to transformsaid slab, in a single cutting operation, into a plurality of discreteportions each of whose through thickness is correlated with andcorresponds to a through thickness of said slab and each of whosedimensions in breadth and height are substantially less than breadth andheight dimensions of the slab from which said portions are cut.

22. In an ice cube making machine including ice slab forming means andice slab dissecting means,

a control system for sequentially cycling ice production and iceharvesting, said control system comprising:

timer means providing a first time period for production of ice on saidice slab forming means, and a second time period for freeing said icefrom said ice slab forming means; and

temperature sensing and responsive means for detecting the freeing ofsaid ice from said ice slab forming means, said' temperature sensing andresponsive means being connected electrically in parallel with saidtimer means;

whereby said temperature sensing and responsive means, upon detectingthe freeing of said ice from said ice slab forming means, operates to`override said timer means thereby terminating said ice harvesting priorto elapse of said second time period.

23. A control system as set forth in claim 22 wherein said timer meansis a motor-driven electrical time switch, and wherein said temperaturesensing and responsive means is a thermostatically controlled electricalswitch.

24. A control system as set forth in claim 22 wherein said temperaturesensing and responsive means `includes a thermostatically controlledelectrical switch responsive to elevation in temperature of said iceslab forming means resulting from freeing of said ice from said ice slabforming means.

25. In an ice maker apparatus including means for forming a slab of iceand means for causing said slab to bear upon ice-cutting means fordissecting said slab, said ice-cutting means including a frame andframe-carried ice-cutting elements; the improvement wherein in use saidice-cutting elements define a lattice of electrically resistively heatedwire means lying in substantially the same plane and comprising crossingwires electrically connected at crossover points and forming a networkof closed meshes within said frame, and further comprising electricalcircuit r-neans operatively coupled to said ice-cutting elements anddeveloping resistively generated thermal energy therein for heating ofsaid elements to cut through said slab of ice bearing thereon.

26. The structure as set forth in claim 1 and further comprising anevaporator plate, and means supplying water to an underside of saidplate to form a slab ot' ice thereon.

27. The structure as set forth in claim 25 wherein said network definesa plurality of electrically conductive paths of substantially uniformvoltage gradient; whereby lineally equal incremental segments of saidwire means forming said network are electrically resistively heated toessentially the same temperature.

28. The structure as set forth in claim 25 wherein said network ofclosed meshes comprises a plurality of wires dening conductive paths ineach of which there is substantially the same voltage gradient.

29. The structure as set forth in claim 1 wherein said lattice extendsbetween two spaced substantially parallel References Cited UNITED STATESPATENTS 6/1954 Ayres et al 62-320 X 2/1962 Jaeger 62-347 X 1/ 1965Swanson 62-320 11/ 1965 Cordes 62-233 X 4/ 1929 Brizzolara 62-62 10ROBERT A. OLEARY, Primary Examiner.

W. E. WAYNER, Assistant Examiner.

U.S. Cl. X.R.

bus bars and wherein said ice cutting elements traverse 15 62-233, 320,352; 219-201; 62--137 non-linear conductive paths between said bus bars.

UNITED STATES PATENT oFFICE CERTIFICATE 0F CORRECTION-- Patent No.3,423,949 January Z8, 1969 Meldon Gerald Leeson et al.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 5,

Column 1, line 56, "the" should read an line 62, "potrions" should readportions line 71, "is" should read in Column 8, line 64, after "woven"insert wire Signed and sealed this 31st day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, JR.

